What is the cause of an intractable cough?

From the Guidelines

In patients with intractable cough, a systematic approach to diagnosis and treatment is essential, and the most common causes of cough, such as upper airway secretions, asthma, and gastroesophageal reflux disease (GERD), should be considered first. For immediate relief, try over-the-counter options like dextromethorphan (Robitussin DM) 10-20 mg every 4 hours or guaifenesin (Mucinex) 600-1200 mg twice daily to thin mucus 1. Honey (1-2 teaspoons) can soothe throat irritation, while lozenges containing benzocaine provide temporary numbing. For nighttime relief, consider diphenhydramine (Benadryl) 25-50 mg before bed. Stay hydrated with 8-10 glasses of water daily and use a humidifier to moisten airways.

In patients with chronic cough, systematically direct empiric treatment at the most common causes of cough (ie, upper airway secretions, asthma, nonasthmatic eosinophilic bronchitis, and GERD) 1. Therapy should be given in sequential and additive steps because more than one cause of cough may be present. Patients with a chronic cough who smoke should be counseled and assisted with smoking cessation. In a patient with cough who is receiving an ACE inhibitor, therapy with the drug should be stopped and the drug should be replaced 1.

Some key points to consider in the management of intractable cough include:

• The importance of a thorough medical history and physical examination to identify potential causes of cough 1
• The use of empiric treatment for common causes of cough, such as upper airway secretions, asthma, and GERD 1
• The consideration of less common causes of cough, such as pulmonary embolism, high-altitude exposure, and mediastinal masses, if the cough persists despite treatment for common causes 1
• The potential for cough to be a symptom of an underlying condition, such as connective tissue disease or inflammatory bowel disease, and the need for further evaluation if the cough is persistent and unexplained 1

Overall, the management of intractable cough requires a systematic and thorough approach to diagnosis and treatment, with consideration of both common and less common causes of cough. The goal of treatment should be to address the underlying cause of the cough, rather than just suppressing the symptom, and to improve the patient's quality of life 1.

From the FDA Drug Label

Warnings ... Ask a doctor before use if you have • chronic cough that lasts as occurs with smoking, asthma or emphysema • cough that occurs with too much phlegm (mucus) Stop use and ask a doctor if • cough lasts more than 7 days, cough comes back, or occurs with fever, rash or headache that lasts.

The drug label does not explicitly address intractable cough. However, it does provide guidance on chronic cough and when to ask a doctor or stop use.

• Chronic cough that lasts, such as with smoking, asthma, or emphysema, requires consultation with a doctor before use.
• Cough lasting more than 7 days, or recurring, or accompanied by fever, rash, or headache, necessitates stopping use and consulting a doctor. Given the information, intractable cough is not directly addressed, but it can be inferred that any persistent or severe cough should be evaluated by a healthcare professional 2.

From the Research

Intractable Cough Treatment Options

• Pharmacological treatments for intractable cough include dextramethorphan, opioid cough suppressants, benzonatate, inhaled ipratropium, and guaifenesin 3
• Nebulized lidocaine has been shown to be effective in suppressing cough, with minimal side effects such as dysphonia, oropharyngeal numbness, and bitter taste 3
• Antitussive preparations, including combinations of codeine or dextromethorphan with antihistamines, decongestants, and expectorants, can provide symptomatic relief for dry cough 4

Management of Chronic Cough

• Chronic cough can be caused by various etiologies, but four conditions account for most cases: upper airway cough syndrome, gastroesophageal reflux disease/laryngopharyngeal reflux disease, asthma, and nonasthmatic eosinophilic bronchitis 5
• Evaluation of chronic cough should include clinical assessment, spirometry, and empiric treatment, with referral to a specialist if necessary 5
• Guaifenesin, a mucoactive drug, can provide relief for wet cough and chest congestion due to the common cold, and is also used in the management of chronic bronchitis 6

Comparison of Cough Syrups

• A clinical trial comparing the effectiveness of three cough syrups found no statistically significant differences among treatment groups, suggesting that codeine, dextromethorphan, and guaifenesin are equally effective in relieving cough symptoms 7
• The choice of cough syrup may depend on individual patient needs and preferences, as well as the presence of any underlying conditions 7